DNA replication is the process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules.
The heart pumps oxygenated blood to the body and deoxygenated blood to the lungs. In the human heart there is one atrium and one ventricle for each circulation, and with both a systemic and a pulmonary circulation there are four chambers in total: left atrium, left ventricle, right atrium and right ventricle.
The heart is the central organ of the circulatory system, and pumps blood into the blood vessels which carry it to all the body parts. All these events occur with each heartbeat. The average heart rate in a normal person is 72 beats per minute, so one can imagine the speed at which blood flows through the body.